In recent years, accompanied by the diversification of various food materials, food additives, foods or beverages (including articles of taste), fragrances or cosmetics, sanitation materials, sundries, pharmaceuticals and the like, new demands for a fragrance to be used therein have been increasing, and concerns have been directed toward the development of aromatic materials having a highly-scenting unique odor. Also, with the recent uprush of the nature-oriented style of people and also from the safety point of view, great concerns have been directed toward the development of new aromatic materials derived from natural compounds, or identical or similar to the natural compounds, with regard to highly-scenting musk-feeling fragrances by which the natural environment can be imaged characteristically.
On the other hand, muscone as a typical example of the musk-feeling fragrances is the main aromatic component of natural musk, and contained in an amount of approximately from 0.5 to 2.0% in the natural musk. Muscone was discovered by Walbaum in 1906, and its chemical structure was determined by Ruzicka in 1926 as 3-methylcyclopentadecanone.
By the efforts of a large number of researchers thereafter, presently it is known that the natural muscone is (−)-(R)-3-methylcyclopentadecanone; that muscone is now on the market and can therefore be easily obtained because of the establishment of chemical synthesis method of muscone; that the synthesized article is a racemic form as a mixture of l-form and d-form of muscone; that the l-form and d-form of muscone obtained by optical resolution, namely (−)-(R)-form and (+)-(S)-form, can be obtained from the racemic form; that the optically active muscone can also be synthesized making use of an asymmetric synthesis; that when odors of the (−)-(R)-form and (+)-(S)-form are compared, the (R)-form has a strong musky odor having diffusiveness (threshold: 3 ppm), while the (S)-form has a chemical, spread-less and poor weak musky odor (threshold: 10 ppm) and, as a result, the (R)-form is about 3 times larger than the (S)-form regarding the strength of smell, and the like (e.g., see Non-patent Reference 1 and Non-patent Reference 2).
Based on the superior aromatic quality and the like of (−)-(R)-muscone, there is a report, for example, on a fragrance composition which can keep a highly-scenting odor for a prolonged period of time, in which at least one species selected from androstenols and 3-methyl-2-hexenoic acid is allowed to be coexistent with (−)-(R)-muscone (Patent Reference 1).
However, the muscone conventionally used in fragrances or cosmetics is (−)-(R)-muscone or a racemic form as an equivalent mixture of (R)-form and (S)-form of muscone.
Patent Reference 1: JP-A-7-324196
Non-patent Reference 1: “Gousei Kouryou, Kagaku to Syouhin Chishiki, (Synthetic Aromachemicals, Chemistry and Merchandise Knowledge)” pp. 492-497, written by Motoichi Indoh, published Mar. 6, 1996, from The Chemical Daily Co., Ltd.
Non-patent Reference 2: “Gosei Kouryou no Saisin Gijutsu (The Recently Techniques on Synthetic Aromachemicals)” pp. 72-90, published by CMC Publishing CO., LTD., 1982